Process of making zinc sulfid.



PATENT Trice.

EMIL BERINGER, OF CHARLOTTENBURG, GERMANY.

PROCESS 0F MAKING ZINC SULFID.

SPEQFZIFIGATIUN forming part of Letters Patent No. 666,300, datedJanuary 22, 1901.

Application filed M 31, 1900. b'erial No. 18,607. (No specimens.)

To (all whont it 77'M7/Z/ concern:

Be it known that I, EMIL BERINGER, manufacturer, royal Prussiancommercial counselor, a subject of the King of Prussia, GermanEmperor,residing at l Sophienstrasse,in the city of ()harlottenburg,Kingdom of Prussia, and German Empire, have invented a certain new anduseful Process for Manufacturing Sulfid of Zinc Suitable for Paints,with Simultaneous Formation of Rhodanates, of which the following is aspecification.

This invention has reference to a process for the formation of sulfid ofzinc by means of which it is possible to adapt the same to themanufacture of a white-colored substitute for zinc-white, white lead,lithopone, and similar paints of good covering qualities,both inadmixture with water and varnishes. This process, which at the same timeyields rho- I am aware that a process for the manufacture of guanidinsalts with sultid of zinc as a by-product has already been described inGerman Patent Specification No. 97,820. This process, however, where theguanidin salt is formed by the decomposition of the sulfo-cyanid ofammonia and which is carried on by subjecting the materials to a dryheating process, differs from my invention, inasmuch as it does notdisclose means for manufacturing a snlfid of zinc adaptable for paintingpurposes, the sullid of zinc being only obtained thereby as a by-productof no commercial importance, and then only in the case of oxid of zincbeing used for the heavy metal oxid forming a part of the processreferred to. My invention, on the contrary, which avoids thedecomposition of the sulfocyanid and is carried on in solution, isintended for the manufacture of sulfid of zinc possessing certainvaluable properties, While the simultaneous formation of sulfo-cyanidsor rhodanates is of but secondary importance in my process, which alsoavoids the inconveniences and drawbacks of the process heretofore in useresulting from an excessive temperature and from other sources.

In order to produce sulfid of zinc adapted for use as a paintingmaterial, it is necessary to avoid any undue rise of temperature and toconduct the process in a closed Vessel provided with an agitator, thetemperature being rapidly raised above 102 Fahrenheit in order toobviate the formation of sulfo-carbonate of ammonia, which, though itwill be decomposed on prolonged boiling, will be sure to impair thephysical condition of the sulfid of zinc formed. The process is thenconducted, preferably, at a temperature of 212 Fahrenheit, so as toavoid decomposition of the product, which will take place when thetemperature is raised too high-say to nearly 300 Fahrenheit, forinstance.

In order to carry my invention into effect, I prefer to use a digesterwith an interior lining of enamel, into which is placed the ammoniacalzinc solution, made up, for instance, of about two hundred and thirtypounds of sulfate of zinc, about one hundred gallons of water, and abouttwo hundred and thirty pounds of ammoniaof 0.91 specific gravity. I thenadd about sixty pounds carbon bisulfid, close the digester, and raisethe temperature rapidly to 212 Fahrenheit, keeping the mixtureconstantly stirred all the time, the pressure rising to sixty pounds bythis time. After four hours the pressure begins to decline, while thetemperature is maintained at 212 Fahrenheit, and after ten hoursdigestion the process is finished, the pressure having gone down toabout twenty-two pounds. It may be mentioned that the yield in thisprocess, both of sulfid of Zinc and of sulfo-cyanids, is almosttheoretical in case of an excess of ammoniacal solution of zinc, saltbeing employed, as in the above example. After the removal of the sulfidof zinc, which is utilized as a color or paint, the ammonia may berecovered from the sulfo-cyanid of ammonia by treatment with quicklime,forming sulfo-cyanid of calcium, from which hydrocyanic acid may beobtained by treatment with nitric acid. It is obvious that inasmuch asin this process only so much of the ammonia will escape immediaterecovery as corresponds to the nitrogen necessary for the formation ofthe sulfo-cyanid group, and in view of the possibility of recoveringeven the rest of the nitrogen in the form of hydrocyanic acid, a greatadvantage, from an economical point of View, is realized over theprocesses heretofore known, where the ammonia of the ammonia salt of thesulfo-cyanid was also decomposed. The sulfid of zinc thus obtained,which after being freed from the liquor and washed is in a state of veryfine distribution, is then dried and ground by porcelain grinders or byany other suitable means.

That I claim, and desire to secure by Letters Patent, is

A process for the formation of sulfid of zinc suitable for themanufacture of white EMIL BERINGER.

Witnesses:

WOLDEMAR HAUPT, HENRY HAsPER.

